Snatch-block



T. R. FERRALL.

SNATGH BLOCK.

Patented Nov. '29, 1887 I %TNEEEEE f Fig. 3-

UNITED STATES.

PATENT OFFICE.

THOMAS R. FERRALL, OF BOSTON, MASSACHUSETTS.

SNATCH-BLOCK.

SPECIFICATION forming part of Letters Patent No. 373,972, dated November 29, 1887.

' Application filed June 16,1886. Serial No. 205,365. (No model.)

To all whom it may concern.-

Be it known that I, THoMAs- R. FERRALL, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Snatch-Blocks; and I do hereby declare that the same are fully described in the followingspecification, and illustrated in the accompanying drawings.

This invention relates to improvements in snatch-blocks, and it is carried out as follows, reference being had to the accompanying drawings, where- Figure 1 represents a front elevation, and Fig. 2 represents a rear elevation, and Fig. 3 represents a central longitudinal section, of the improved snatch-block.

Similar letters refer to similar parts wherever they occur on the different parts of the drawings.

In the drawings, (1 represents the front or short side of the block, and b represents the rear or long side of it, as usual. Such side pieces may be ofwood or metal, as may be desired, although in the drawings they are represented as being made of wood.

a and b are bent metal bow-straps, fitting over the inside and outside of the respective side pieces, a and b, in the ordinary way.

a and b are bent loops in the upper ends of the respective bow-straps a and b.

c is the pulley spindle, as usual, passing through the bow-straps a b, as well as the sides a and b, and upon such spindle is journaled the sheave d, in the ordinary way.

The lower ends of the side pieces, a b, are united by means of rivets e e, passing through them and the end piece, f, by which the sides a and b are held at a proper distance apart, according to the width of sheave that is used. The lower ends of the bow-straps a/ b are firmly secured to sides a b and end piece, f, by means of the rivet f, as shown. To the loop a is hinged the link 9, the upper end of which is adapted to receive the projection h on the head h, as usual, such projection being provided with a lip, h, so as to hold the head it and link glocked together when the block is in its normal working position, as shown in Figs. 1 and 3.

To prevent the link 9 from getting accidentally detached from the projection h when the hook z is swung at a right angle to the center line of the block, I make on said link 9 a horizontal connectingbar, 9, (shown in Figs. 1 and 3,) outside of which the lip h will drop when turned downward, and thus keep the link g and projection h coupled together until the operator raises the latter and its head hby swinging it on fulcrum h, when the link 9 can easily be swung outward and disconnected from the projection h, there being a sufficient distance between the interior upper end of link 9 and upper side of bar to permit the lip h to pass through when the head'h is raised. To the head h is journaled the hook t, its shank a" passing through a perforation in head h, and riveted or enlarged in its lower end to permit thehook '5 to swivel relative to head h without getting detached therefrom, as usual. To the loop I) is hinged the self-adjusting rocker or intermediate connecting-piece, h, it having for this purpose aspindle, h, in its lower end, that passes through the loop 5, and such spindle may be made or cast in one piece with the rocker h or made separate from it, as may be found most practical. On the head h, opposite to thelocking projection h, is a cylindrical projection or trunnion, h, that passes through a perforation in the rocker k, and is loosely riveted or otherwise secured to it, so that the head h may be permitted to swing relative to the piece is without getting detached from it, as shown in Fig. 3. Snatch-blocks have been made with the hea h hinged directly to the rear bow-strap, and by making blocks in such a manner great care had to be taken to get the right length of the link 9, so as to equalize the strain at both ends of the head h, and to prevent the whole strain from being carried to the trunnion h at one end of the said head h. By interposing between the loop b and the head h the hinged rocker-piece is all such aforesaid objections are overcome, and with it, it is not essential that the link 9 should be of a standard length, for if it should be a little too long or short when the strain of the rope is conveyed to the hook 6 its head h will automatically adjust itself, in consequence of the hinged rocker is, so as to divide the hook-strain equally on both ends of the head h.

There are two advantages gained by having the rocker-piece is arranged as shown and described in a snatch-block-namely, the block can be made and put together ready for use at less expense, as the parts need not be arranged with so great a nicety as when no such intermediate roeker is used, and, further, the strength of the block is materially increased, as the hook z and its head h will automatically adjust themselves relative to the block proper to variations in the direction of the strain of the rope, so as to transfer such strain equally to both ends of the head h, and thus prevent the accidental breaking of the trunnion h In practice I prefer to make the under side of the spindle 7c flat or flattened, as shown in Fig. 3, so as to limit the rocking motion of the piece It by having such flattened surface come in contact with the upper end of the rear side piece, b,- but such spindle may be made of a cylindrical or other form without departing from the essence of my invention.

What I wish to secure by Letters Patent, and claim, is-

1. A snatch-block provided with the rocker is, interposed between the upper end of side piece, b, and one side of head h, as set forth.

2. The combination of the side pieces, a I), having hinged bow-straps a I), the sheave d, the head 71, hinged to bow-strap b, the rocker 7c, and strap a, hinged to link 9 and adapted to be locked on the head projection h by the lip h, as and for the purpose set forth.

3. A snatch-block composed of the sides a b, sheave d, the bow-straps a b, the link 9, hinged to strap a, and rocker k, hinged to strap 1), as described, combined with head h, having projection and lip h h in one end, and spindleh, hinged to rockerk in the other, substantially as set forth.

In testimony whereof I have affixed my signature in presence of two Witnesses.

THOMAS R. FERRALL.

Witnesses:

ALBAN ANDREN, HENRY GrIADBoURN. 

